Network system for distribution



4 Sheets-Sheet 1 ame s PAFQSQNS NETWORK SYSTEM FOR DISTRIBUTION OriginalFiled July 30, 1952 INVENTOR J0/7n5'%rs0n$,

J. S. FARE-SONS NETWORK SYSTEM FOR DISTRIBUTION Original Filed July 50,1952 4 Sheets-Sheet 2 0d. 22, 1935. J 5 PARSQNS 2,018,225

NETWORK SYSTEM FOR DISTRIBUTION Original Filed July 30, 1932 4Sheets-Sheet 5 wsT-E$ss:- INVENTOR @220 22 1225 J; S, ARSON 2,018,225

NETWORK SYSTEM FOR DISTRIBUTION Original Filed July 30, 1932 4Sheets-Sheet 4 .WITNESSES: 2 INVENTOR 5 7% \12/20 5 Faraan.

ATTO EY Patented Oct. 22, 1935 UNlTED STA'E'ES PATENT QFFIQE NETWORKSYSTEM FOR DISTRIBUTION sylvania Application July 30, 1932, Serial No.627,081 Renewed February 26, 1935 13 Claims. (Cl. 175-294) The presentinvention relates to a superimposed frequency system of control andprotection for alternating-current network systems of distribution. Theinvention is a system of control and protection alternative to thecontrol systems disclosed in my United States Patent No. 1,953,126,issued April 3, 1934, and my copending application Serial No. 627,082,both filed on July 30, 1932, and both assigned to Westinghouse Electricdz Manufacturing Company.

in any high frequency arrangement for effecting the control andprotection of an alternatingcurrent network system of distribution, theprovision of tuned circuits or blocking circuits in the respectivefeeders, supplying a common network load circuit may be objectionablefrom the standpoint of initial installation costs. Where such provisionof tuned circuits or blocking circuits in the feeder circuits, supplyingpower to a network load circuit, may be objectionable for economicreasons or where existing network systems of distribution employ theusual sensitive or insensitive directional relay control means, thecontrol system of the present invention may be 25 employed and result inan improved control and protective means for such network systems oftribution.

at is an object of the present invention, therefore, to provide ahigh-frequency control and pro- :70 tective arrangement for analternating-current network system of distribution wherein tunedcircuits or blocking circuits are not necessitated in any of the feederssupplying power to the network load circuit.

33 Another object of the present invention is to provide ahigh-frequency control system for an alternating-current network systemof distribution wherein the high-frequency or other-thannormal frequencycontrol currents are applied 4-) to the respective feeders only for thepurpose of effecting the closure of the network circuitbreakersassociated with such feeder circuits.

Another object of the present invention is to effect the closing of thenetwork circuit breakers 46 associated with any particular feedercircuit when such feeder circuit is disconnected from its associatedsource or bus.

e ive type for controlling the opening of the network circuit-breakers.

Another object of the present invention is to provide ns, in conjunctionwith a superimposed frequency system of control, which permits 55 theconnection of a plurality of feeder circuits,

energized from different sources or buses, to a common network loadcircuit.

A further object of the present invention is to effect the closing ofthe network circuit breakers, associated with any particular feedercircuit, '5 only when the source of other-than-normal frequency currentsis in proper condition for supplying the superimposed frequency currentsto any of the feeder circuits.

A further object of the present invention is to 10 apply theother-than-normal frequency control currents to any of the feedercircuits only for a predetermined time, such timedelay depending uponthe characteristics of the particular network system of distribution tobe controlled and pro- 15 tected.

Further objects and advantages of the present invention will become morereadily apparent from a detailed consideration of the function andsequence of operation of the proposed control apparatus illustrated inthe several drawings.

In the drawings, Figure l. is a schematic singleline diagram of atypical alternating-current system of distribution employing the controlsystem contemplated in the present invention;

Fig. 2 is a schematic diagram of the control means associated with afeeder circuit breaker in an alternating-current network system ofdistribution and the means of applying the otherham-normal frequencycontrol currents to such feeder circuit.

Fig. 3 is a schematic diagram of the control circuit for a networkcircuit breaker utilizing sensitive directional relaying means.

Fig. i is a schematic diagram of the control circuit for a networkcircuit breaker utilizing insensitive directional relaying means.

Referring more particularly to Fig. l, a network load circuit l isindicated as comprising a plurality of interconnected conductors for thepurpose of supplying power to consumers at a proper utilization voltageand this network load circuit or grid i is indicated as being suppliedwith power from a plurality of feeder circuits 2, 3 and i. The feedercircuit 2 is indicated as being energized from a source or bus 6, whilethe feeder circuits 3 and i are indicated as being energized in parallelfrom a second source or bus l. The feeder circuit 2 is connected to thesource or bus 6 by means of a feeder circuit breaker 6S, and the feedercircuits '3 and are connected to the sec source or bus l by means ofsuitable feeder circuit breakers El and ii, respectively.

Each of the feeder circuits 2, 3 and 4 is connected to the network loadcircuit I through suitable distribution or step-down transformers andnetwork circuit-breakers interposed between the secondary windings ofsuch network transformers and the network load circuit. The respectivenetwork transformers, associated with any of the feeder circuit, areindicated by means of the reference numerals on the associated feedercircuit and the letter T. The network circuit breakers associated withthe respective feeder circuits are indicated by the reference numeral ofthe associated feeder circuit and the letter N.

High-frequency relays are associated with each of the networktransformer and network circuit breaker units and are indicated by thereference numeral of the associated feeder circuit and the letter R. Therespective lughfrequency control relays are connected to the feedercircuits on the primary side of the associated network transformerthrough suitable tuned circuits comprising series-connected capacitanceand inductance units which are designated in the drawings by thereference numeral of the associated feeder circuit and the letter (3.

Only the high-frequency control relays are illustrated in Fig. l. of thedrawings, and it is to be understood that such relays are provided onlyfor the purpose of effecting the closure of their associated networkcircuit breakers. The control means for effecting the opening of thenetwork circuit breakers comprises power directional relays of the usualsensitive or insensitive type or other equivalent devices known in theart, depending upon the characteristics desired in any particularnetwork distribution system and such opening control means is notindicated in this figure of the drawings. Reference to one form ofopening control means for the network circuit breakers will beconsidered hereafter with reference to Figs. 3 and 4 of the drawings.

The superimposed frequency control currents are impressed upon therespective feeder circuits supplying power to the network load circuitby means of high-frequency generators I 2 and I3. The high-frequencygenerator 42 is adapted to be connected to the feeder circuit 2 througha. tuned circuit I4, comprising a series-connected capacitance and aninductance, and through a circuit breaker I6. The second high-frequencygenerator I3 is adapted to be connected to the feeder circuits 3 and 4through a tuned circuit I'I, comprising an inductance and a capacitance,and through circuit breakers I8 and I9, respectively.

The circuit breakers I6 and I8, I9 are shown in their open positions,inasmuch as the feeder circuit breakers 8, 9 and I I are shown in theirclosed positions, and the high-frequency generators I2 and I3 arenormally disconnected from the respective feeder circuits 2, 3 and 4when power is being delivered to the network load circuit I from suchfeeder circuits.

The general operation of the control and protective system contemplatedin the present invention may be explained as follows. Assume the networkload circuit I to be deenergized and the feeder circuit breakers 8, 9and II to be in their open positions, the feeder circuit 3 may beconnected to the network load circuit I, by the central stationoperator, in the following manner.

The circuit breaker IB is actuated to its closed position, therebypermitting the high-frequency currents to be applied to the feedercircuit 3 from the high-frequency generator I3. Immediately upon theapplication of such highfrequency currents, an energizing circuit forthe high-frequency relays 3*R is completed from ground through thehigh-frequency generator I3, tuned circuit I'I, circuit breaker I8,feeder circuit 3, tuned circuits il-C, relays 3-2, and back to ground.The relays 3-I-1 are, therefore, effectively energized to close theirrespective contacts and partially complete an energizing circuit forclosing the network circuit breakers 3-N.

After the circuit breaker iii is closed by the central station operator,the operator closes the feeder circuit breaker 9, thereby energi mg thenetwork transformers 3-1. The energization of the secondary windings ofthe transformers 3-T completes the energizing circuits for closing thenetwork circuit breakers 3-N and the transform ers 3-T are thereuponconnected to supply power to the network load circuit i.

As soon as the network circuit breakers 3-N are actuated to their closedpositions, a nicchanical latching means is effective to maintain suchbreakers in their closed position and the high frequency relays 3-11 areineffective to cause any further actuation of the network circuitbreakers.

As will be explained hereafter, the feeder circuit breaker 9 and thenetwork circuit breakers 3-N are adapted to be actuated to their openpositions by means of overcurrent and directional relays, respectively.The conditions under which such circuit breakers are actuated to theiropen position will also be detailed hereafter in a consideration of thespecific control means provided for each breaker.

The sequence of control for connecting the feeder circuit 4 to thenetwork load circuit I is the same as that explained with reference tothe connection of the feeder circuit 3 to the network load circuit I.Inasmuch as the two feeder circuits 3 and 4 are energized from the samesource or bus I, it is unnecessary to synchronize the two feedercircuits and, therefore, it is only necessary to effect the sequentialclosure of the circuit breakers I9 and II.

Assuming the network load circuit I to be deenergized and that it isdesired to connect the feeder circuit 2 to supply power to such networkload circuit, the sequence of control operation is substantially thesame as that described in connection with the feeder circuits 3 and 4.However, assuming the network load circuit I to be energized from thefeeder circuits 3 and/or 4 and that it is desired to connect theadditional feeder circuit 2 to supply power to the network load circuitI, the sequence of control operation is as follows:

The central station operator effects the closure of the circuit breakerI6, thereby connecting the high-frequency generator I2 to the feedercircuit 2 through the tuned circuit I4 and the circuit breaker I6.Immediately upon the application of the other-than-normal frequency currents to the feeder circuit 2, the high-frequency relays 2-R, associatedwith such feeder circuit, are effectively energized and their associatednetwork circuit breakers 2-N are actuated to their closed positions.Upon the closure of the circuit breakers 2-N, a voltage proportional tothe network load circuit voltage is impressed on the network transformerside of the feeder circuit 2 and the station operator synchronizesacross the feeder circuit breaker 8. When the voltages of bus 6 and thefeeder circuit 3 bear a predetermined permissible magnitude andphase-angle relation, the central station operator closes the feedercircuit breaker 8 and the source or bus 6 is synchronized with source orbus I through the network load circuit I, and the feeder circuits 2, 3and/or 4 are connected to supply power to the network load circuit l.

Upon the closing of any of the feeder circuit breakers 8, 9 or if, thecircuit breakers l6, [8 or 19, respectively, are immediately opened todisconnect the high-frequency generators l2 and I3 from the respectivefeeder circuits. This disconnection of the highfrequency generators l2and i3 is effected automatically as soon as the feeder circuit breakers,associated with the feeder circuits 2, 3 or i, are actuated to theirclosed positions by the central station operator.

A time-delay feature is also included in the control circuit, associatedwith the feeder circuit breakers and the circuit breakers connecting thehigh-frequency generators to the feeder circuits and such time-delay isprovided in order to effect the disconnection of the high-frequencygenerators in the event that the feeder circuit breakers are notactuated to their closed position for some reason or other.

The provision of this time delay avoids any possibility of the networkcircuit breakers remaining closed and the network load circuit supplyingthe losses in the associated transformers and feeder circuit when thefeeder circuit breaker remains open. The high frequency generators arealso automatically disconnected from their associated feeder circuitsunder condtions when a fault obtains on the feeder circuit and theassociated network circuit breakers remain open.

When sensitive power directional relays are utilized for effecting theopening of the network switches, the high frequency relays are soconnected and arranged as to prevent the effective energization of thepower directional relays when the feeder circuit breaker remains open,or as long as the high frequency generator remains connected to theassociated feeder circuit. This arrangement avoids any possibility ofpumping of any of the network switches due to the failure of the centralstation operator to close the feeder circuit breaker or when the feedercircuit is faulty when the high frequency currents are applied thereto.

The control apparatus, associated with the feeder circuit breakers andthe circuit breaker associated with the high-frequency sources adaptedto be connected to such feeder circuits, is so arranged that thehigh-frequency generators may only be connected to the feeder circuitswhen the feeder circuit breakers, in such circuits, are in their openposition.

The sequence of control for effecting the conmotion of one or more ofthe feeder circuits to the network load circuit will now be consideredwith reference to Fig. 2 of the drawings.

The feeder circuit breaker 8, associated with the feeder circuit 2, isprovided with pallet switches 24 and 26 and stationary contacts 2'1, 29and 35. When the feeder circuit breaker 8 is in its open position, thepallet switch 24 is adapted to bridge the stationary contacts 28 and thepallet switch 26 is adapted to bridge the stationary contacts 3!.However, when the feeder circuit breaker 8 is actuated to its closedposition, the pallet switches 24 and 26 are moved out of engagement withthe stationary contacts 28 and 3 l, respectively, and such palletswitches are adapted to bridge the stationary contacts 21 and 29,respectively.

The feeder circuit breaker 8 is also provided with suitable closing andtripping mechanisms, the closing mechanism including a closing coil orenergizing winding 32 and the tripping mechanism including a trippingcoil or energizing winding 33.

The circuit breaker l6, associated with the high-frequency generator I2,is provided with a pallet switch 34 and stationary contacts 35 and 3?.When the circuit breaker I 6 is in its open position, the pallet switch3 1 is adapted to bridge the stationary contacts 31, and when thecircuit breaker is in its closed position, the pallet switch 3-5 isadapted to bridge the stationary contacts 36. This circuit breaker isprovided with suitable closing and tripping mechanisms, the closingmechanism including a closing coil or energizing winding 38 and thetripping mechanism including a trip coil or energizing winding 39.

The feeder circuit breaker 3 is adapted to be actuated to its openposition in accordance with predetermined over-current conditionsexisting on the feeder circuit 2 as a result of faults or other abnormalsystem conditions. Over-current relays n, having energizing windings s?energized from star-connected current transformers 43, associated withthe feeder circuit 2, are provided for the purpose of effecting theopening of the feeder circuit breaker 8 upon the occurrence ofpredetermined magnitudes of current flowing in the feeder circuit 2.Each of the over-current relays M is provided with moving contacts 44and stationary contacts 45.

A suitable direct-current source, such as battery 45, is provided forcontrol purposes and the stationary contacts 45, of the over-currentrelays 4!, are connected in parallel and are adapted to effect theencrgization of the trip coil 33, associated with the feeder circuitbreaker 8, by means of an energizing circuit including the source 41when such feeder circuit breaker is in its closed position and apredetermined over-current condition exists on the feeder circuit 2. Apush-button switch 45 is also associated with the trip coil 33 and thecontacts thereof are adapted to complete a parallel circuit with thecontacts of relays The switch is provided in order to enable the centralstation operator to disconnect the feeder circuit 2 during times oflight load and/or when it becomes desirable to isolate the feedercircuit Assume first that the buses h and l are energized from the samesource and that only the feeder circuits 2 and 3 are adapted to beconnected to supply power to a common network load and, furthermore,that feeder circuit breakers 8 and 9 are in their open position; themanner of connecting the feeder circuit 2, to supply power to thenetwork load circuit, will now be detailed.

Relays 6t and iii and push button switch 66 are associated with thecontrol circuits of the feeder circuit breaker and the circuit breakerif, and the relay fit is provided with a dashpot or other time-delaymeans, the time delay imparted to such relay depending upon theparticular characteristics desired in any alternating current networksystem of distribution. The reiay so is provided with an energizingwinding 55, stationary contacts 52, 53, 5d and 56, and moving contacts57, 58 and 59. The time delay relay 6! is provided with an energizingwinding 62, stationary contacts 63 and moving contact 5:3.

Since the feeder circuit 3 is not connected to the network load circuitand the network load circuit is completely deenergized, the centralstation operator closes the push button switch 66, thereby completing anenergizing circuit for the winding 5| of relay 49. This energizingcircuit may be traced from the positive terminal of the direct-currentsource 41, through a currentlimiting resistance 61, push button switch66, energizing winding 5|, pallet switch 24 and staticnary contacts 28of the feeder circuit breaker 8, and thence to the negative terminal ofthe direct-current source 41. The relay 49 i thereby effectivelyenergized to bridge the stationary contacts 52, 53 and 54 by the movingcontacts 51, 58 and 55!, respectively.

The bridging of stationary contacts 52 by the moving contact 51completes a holding circuit for the energizing winding 5| and suchholding circuit merely by-passes the contacts of the push button switch65. The bridging of the stationary contacts 53 by the moving contact 58sets up an energizing circuit for the winding 62 of the timedelay relay6|. This energizing circuit may be traced from the positive terminal ofthe directcurrent source i-l', stationary contacts 53 and moving contact58 of the relay 5|, energizing winding 52 of the time-delay relay 5|,and thence to the negative terminal of the direct-current source 41.

The bridging of the stationary contacts 54 by the moving contact 59completes an energizing circuit for the closing coil 38 of the circuitbreaker l6. This energizing circuit may be traced from the negativeterminal of the direct-current source 41, stationary contacts 54 andmoving contact 59 of the relay 5|, energizing winding 38 associated withthe closing mechanism of the circuit breaker l6, stationary contacts 3'!and pallet switch 34 of the breaker 6, and thence to the positiveterminal of the direct-current source 41.

The circuit breaker H3 is thereupon actuated to its closed position andthe pallet switch 34 is moved out of engagement with the stationarycontacts 31, thereby open-circuiting the energizing circuit for theclosing coil 38, and the sta tionary contacts 36 are bridged by thepallet switch 34.

The closing of the circuit breaker I6 connects the highfrequencygenerator |2 of phase A of the feeder circuit 2 through the tunedcircuit I4, thereby applying the other-than-normal frequency currents tothe feeder circuit 2. The high-frequency relays at the network loadcircuit end of the feeder circuit 2 are thereupon energized to effectthe partial completion of the closing circuit of their associatednetwork circuit breakers. The network circuit breakers are thereuponadapted to be actuated to their closed positions immediately upon theclosure of the feeder circuit breaker 8.

Since the feeder circuit breaker 8 is in its open position, thecther-than-normal frequency currents, applied to the feeder circuit 2 bythe highfrequency generator l2, are not permitted to circulate in otherparts of the network system even though no blocking circuits or tunedcircuits are included in the feeder circuits.

After the circuit breaker H3 is actuated to its closed position, thecentral station operator closes the push button switch 48, associatedwith the energizing winding 32 of the feeder circuit breaker 8, and anenergizing circuit for the winding 32 is thereby completed. Thisenergizing circuit may be traced from the positive terminal of thedirect-current source 41, through the push button switch 48, energizingwinchng 32, stationary contacts 3| and pallet switch 25 of the feedercircuit breaker 8, and thence to the negative terminal of thedirect-current source 41. The feeder circuit breaker 8 is therebyactuated to its closed 5 position and the pallet switches 24 and 26bridge the stationary contacts 21 and respectively.

The bridging of the stationary contacts 21 by the pallet switch 24completes an energizing circuit for the trip coil 39, associated withthe cir- 10 cuit breaker l6, and such energizing circuit may be tracedfrom the negative terminal of the direct-current source 47, stationarycontacts 21 and pallet switch 24 of the feeder circuit breaker 8, tripcoil 39, stationary contacts 36 and pallet switch 34 of circuit breakeri5, and thence to the positive terminal of the direct-current source 41.The circuit breaker I5 is actuated to its open position and thehigh-frequency generator I2 is disconnected from the feeder circuit 2.It will be noted that whenever the feeder circuit breaker 8 is in itsclosed position, the circuit breaker |6 is actuated to its open positionand the high-frequency generator 52 is never connected to the feedercircuit 2 when the feeder circuit breaker 8 is in its 25 closedposition.

Assuming the circuit breaker 8 to be actuated to its closed positionbefore the end of the time for the 'tiine 'delay relay 5| to bridge thestation ry contacts 33 by the moving contact 64, 39 the op e of thestationary contacts 53 of the cts the deenergization of the windingire-delay relay 6|. The winding 5| of the relay i3 is also deenergizedinasmuch as the pallet switch 24 is moved out of engagement with thecontacts 28 of the feeder circuit breaker B when the circuit breaker 8is actuated to its closed position. The circuit across stationarycontacts 52 of the relay 49 is also broken, thereby interrupting theholding circuit for the energizing 40 winding 5| of the relay 49.

Assume now that the circuit breaker l5 has been actuated to its closedposition as described hereinbefore and that the central station operatordoes not actuate the push button switch 48 to effect the closing of thefeeder circuit breaker 8. The time-delay relay 6| is energized for asufliciently long period to effect the bridging of its stationarycontacts 63 by the moving contact 54. The bridging of the stationarycontact 63 shunts 50 the energizing winding 5| of the relay 49, therebyresulting in the effective deenergization of the relay 49 and thecontacts 58 and 59 are moved out of engagement with the stationarycontacts 52, 53 and 54, respectively, while the stationary 55 contacts55 are bridged by the moving contact 59. The bridging of the stationarycontacts 55 com pletes a tripping circuit for the trip coil 39 of thecircuit breaker l5 and such energizing circuit may be traced from thenegative terminal of the direct-current source 41, stationary contacts56 and moving contact 59 of the relay 49, trip coil 39, stationarycontacts 35 and pallet switch 34 of the circuit breaker l5, and thenceto the positive terminal of the direct-current source 41.

The circuit breaker |5 is thereby actuated to its open position and thehigh-frequency generator 2 is disconnected from the feeder circuit 2.The tripping circuit completed by the stationary contacts 55 and movingcontact 59, of the relay .9, is in parallel with the tripping circuitfor the circuit breaker it which is completed through stationarycontacts 2? and pallet switch 21, associated with the feeder circuitbreaker It follows, therefore, that the circuit breaker I6 is actuatedto its open position to thereby disconnect the high-frequency generatorl2 from the feeder circuit 2 when the central station operator does notactuate the push button switch 48 within a predetermined time after theapplication of the other-than-norinal frequency control currents to thefeeder circuit 2, and also when the feeder circuit breaker 8 is actuatedto its closed position by the central station operator.

Upon the occurrence of any fault or predetermined abnormal currentcondition existing on the feeder circuit 2, one or more of theover-current relays id is effectively energized to bridge the stationarycontacts as by the moving contact 44, with the result that a trippingcircuit for the feeder circuit breaker 8 is completed, such circuitbeing traced from the positive terminal of the direct-current source ll,stationary contacts it and moving contacts M of one or more of therelays ll, trip coil 33, stationary contacts 29 and pallet switch 25 ofthe feeder circuit breaker 8, and thence to the negative terminal of thedirect-current source il. It follows, therefore, that the feeder circuitbreaker 8 is actuated to its open position upon the occurrence of anyfault or predetermined abnormal current condition on the feeder circuit2 and the resultant effective energization of one or more of theover-current relays t i.

The opening of the network circuit breakers at the network load circuitend of the feeder circuit 2 is accomplished by suitable directionalrelays, the operation of which will be explained hereinafter withreference to Figs. 3 and 4 of the drawn gs. It may be noted, however,that such directional relays may be of either the sensitive orinsensitive type and are not responsive to the other-than normalfrequency control currents in effecting the opening of their associatednetwork circuit breakers.

In the event that the feeder circuits 2 and 3 are energized fromdifferent sources or buses, as indicated in Fig. l of the drawings, thesequence of operation of the control scheme, associated with the feedercircuit breaker 8 and the circuit breaker i6, is altered. Assume thatthe feeder circuit breaker 9 is in its closed position and that thefeeder circuit 3 is supplying power to the network load circuit, towhich the feeder circuit 2 is adapted to be connected, and that it isdesired to connect the additional feeder circuit 2 to supply power tothe same network load circuit. The control of the feeder circuit breakerii and the circuit breaker I6 is substantially as describedhereinbefore.

Briefly, the central station operator effects the closing of the circuitbreaker IE to connect the high-frequency generator E2 to the feedercircuit 2 by actuating the push button switch 56. This application ofthe other-than-normal frequency control currents to the feeder circuit 2results in the effective energization of the high-frequency relays atthe network load circuit end of the feeder circuit 2. Thesehigh-frequency relays complete the closing circuits of their associatednetwork circuit breakers with the result that these breakers are closedand a voltage, proportional to the network load circuit voltage, ap-

pears on the network transformer side of the feeder circuit breaker 8.The central station opcrater then synchronizes this network load circuitvoltage and the voltage of the bus or source 5, and, when the respectivevoltages bear predetermined permissible magnitude and phase-anglerelations, the operator actuates the push button switch 48 to effect theclosing of the feeder circuit breaker 8. As explained hereinbefore, theclosing of the feeder circuit breaker 8 results in the actuation of thecircuit breaker [6 to its open position, thereby disconnecting thehigh-fre- 5 quency generator i2 from the feeder circuit 2. The source orbus 6 is, therefore, synchronized with the source or bus 7 through thenetwork load circuit.

The sensitive type relay control apparatus as- 10 sociated with thenetwork circuit breakers and the network transformers is shown in Fig. 3of the drawings. Inasmuch as the relay apparatus is similar'for each ofthe network circuit breakers, only the control circuits for one of suchcircuit breakers are illustrated. The relay control apparatus is shownin conjunction with one of the network transformers Z-T and associatednetwork circuit breaker Z-N, and the network transformer 2-T is adaptedto supply power to the network load circuit I through the networkcircuit breaker Z-N. A second network transformer 3-T is illustrated asbeing adapted to be connected to the same network load circuit I throughnetwork circuit breaker 3-N.

The other-than-normal frequency control currents superimposed upon therespective feeder circuits, adapted to supply power to the network loadcircuit 1, are utilized only for the purpose of effecting the closure ofthe network circuit breakers 2-N and 3-N. In effecting the closing ofthe network circuit breaker Z-N, a suitable tuned circuit Z-C isassociated with phase A of the feeder circuit on the primary side of thenetwork transformer Z-T, and a highfrequency relay 2-R is so connectedand arranged to be energized in accordance with such other-than-normalfrequency currents. The high-frequency relay 2-R is provided withenergizing winding H, stationary contacts 12, 13, I4 and f6 and movingcontacts 71, 78, i9 and 8|.

The tuned circuit Z-C comprises a series-connected capacitance and aninductance connected to phase A of the feeder circuit on the primaryside of the network transformer 2-T, and such 5 series-connected circuitis connected to the energizing winding H of the high-frequency relayZ-R, and thence to ground.

Upon the application of the other-than-normal frequency control currentsto the feeder circuit, associated with the network transformer 2-T, theenergizing winding H of the high-frequency relay Z-R is effectivelyenergized to bridge the stationary contacts l2, f3, 14 and 16 by themoving contacts 11, 18, 19 and 8|, respectively, and upon the removal ofthe other-than-normal frequency control currents from the associatedfeeder circuit, the high-frequency relay Z-R is deenergized and thecontacts 11, 18, 19 and 81 thereof are moved out of engagement with thestationary contacts 12, 13, I4 and '18, respectively. Relays 84 and 86are associated with the control circuit for effecting the closure of thenetwork circuit breaker 2-N, and the relay 84 is provided with anenergizing winding 81, stationary contacts 88 and 89 and moving contactsBI and 92. The relay 86 is provided with an energizing winding 93,stationary contacts 94, 96, 91 and 98, and moving contacts 99, If.

The network circuit breaker 2-N is provided 7 withsuitable closing andopening mechanisms, the closing mechanism including a closing coil orenergizing winding 1G3 and the opening or tripping mechanism includingan energizing winding I02. The network circuit breaker Z-N is alsoprovided with stationary contacts I84, I06 and pallet switch I81.

When the energizing winding 8'1, of the relay 84, is deenergized, themoving contacts 9| and 92 are out of engagement with the stationarycontacts 38 and 89. However, when the winding El is effectivelyenergized, the stationary contacts 88 and 89 are adapted to be bridgedby the moving contacts BI and 92, respectively. When the winding 83 ofthe relay 86, is deenergized, the moving contacts 98 and IDI thereof areadapted to bridge the stationary contacts 96 and 98, re spcctively. Whenthe winding 93 is energized, the moving contacts 99 and I (ll areadapted to bridge the stationary contacts 94 and 97, respectively.

When the network circuit breaker 2-N is in its open position, the palletswitch IN is adapted to bridge the stationary contacts i855, and, whenthe network circuit Z-N is actuated to closed position, the palletswitch I8"! bridges the stationary contacts HM.

In order to effect the opening of the network circuit breaker Z-N,directional relays !88 are provided. These directional relays areillustrated generically as icing of the sensi "ye type and are shownschematically as compi sing C- magnet structures 588, current windingsIli, voltage windings H2, disc members Ii-i, spindles or shafts H4,restraining springs I I6, stationary contacts II? and moving contactsllil. The springs I I ii are provided for the purpose of maintaining themoving contacts 558 out of engagement with the stationary contacts Iilwhen the relays I98 are deencrgized.

The current windings i ii adapted to be energized in accordance wi he manitude and phase position of the current flowing in the re-- spectivephases of the circuit between the net- Work transformer 2-T and thenetwor; load circuit I. This energization of the current windings III iseffected by means of star-ccnnected current transformers havingsecondary windings I I9, the star-connection point being grounded. Therespective phases of the circuit between the network transformer B-T andthe network load circuit I are indicated from left to right as A, B andC. The voltage windings N2 of the directional relays i are adapted to beenergized in accordance with the voltage of the respective phases A, BC. These voltage windings H2 are each adapted to be connected in circuitfrom one of the phases to ground.

Assuming the network circuit breakers Z-N and 3-H to be in their openpositions and that i circuit i is not energized from any other to orcircuits or network transformers, the mam r of eff cting the closure ofthe network circuit r 2--N is as follows. Upon the application of theother-than-normal ire quency currents to the feeder circuit associatedwith the networ: transformer LT, the winding II of the high-frequencyrelay 2-8. is effectively energized to bridge the stationary contacts12, I3, I4 and Iii by the moving contacts 11, I8, I9 and SI,respectively. The stationary contacts I2, of the high-frequency relay2-H, and the stationary contacts 38, of the relay 34, are connected inparallel and one terminal of the energizing winding 8!, of the relay 84,is connected to one of the stationary contacts 88.

The remaining terminal of the energizing winding Bl is connected to oneof the stationary contacts 89, of the relay 84, and to one of thestationary contacts I06 of the network circuit breaker Z-N. Theremaining stationary contact I86 is connected to one of the stationarycontacts 91 and 88 of relay 86. The remaining stationary contact 88, ofthe relay 35, is connected to phase A of the circuit between the networktransformer Z-T and the network load circuit I on the transformer sideof the network circuit breaker Z-N. The remaining stationary contact 91is connected to phase A on the network load circuit side of the networkcircuit breaker 2-N and to one terminal of the energizing winding 93 ofthe relay 38. The remaining terminal of the energizing winding 93 isconnected to one of the stationary contacts 94 and to phase C on thenetwork load side of the network circuit breaker r The remainingstationary contact 83, of relay 84, is connected to the remainingstationary contact 94, of relay 86, to one of the stationary contacts 88and to one terminal of the energizing winding I83 associated with theclosing mechanism of the network circuit breaker ?.--N. The remainingterminal of the energizing winding I83 is connected to the remainingstationary contact 89 of relay 84. The remaining stationary contact 96,of relay 88, is connected to phase 0 on the network transformer side ofthe network circuit breaker 2-N.

The stationary contacts IIl', of the directional relays I08, areconnected in parallel and one of the parallel connections iselectrically connected to phase C on the network transformer side of thenetwork circuit breaker 2-H, while the remaining parallel connection isconnected to one terminal of the energizing winding I82 associated withthe tripping mechanism of the network circuit breaker 2-N. The remainingterminal of the energizing winding E82 is connected to one of thestationary contacts I04, of the network circuit breaker Z-N, and theremaining stationary contact I84 is connected to phase A on the networktransformer side of the network circuit breaker 2-N.

Upon the effective energization of the winding II, of the high-frequencyrelay 2-H, the stationary contacts "I2 are bridged by the moving contactI1 and an energizing circuit for the winding 81, of relay 84, iscompleted, such energizing circuit being traced from phase C, of thenetwork transformer 2-T, stationary contacts 86 and moving contact 99 ofrelay 88, stationary contacts I2 and moving contact ll of relay 2-H,energizing winding 81, of relay 84, stationary contacts I06 and palletswitch IUI of the network circuit breaker 2-N, stationary contacts 86and moving contact IUI of relay 86, and thence to phase A of the networktransformer Z-T.

The energization of the relay 84 effects the bridging of the stationarycontacts 88 and 88 by means of the moving contacts 91 and 92,respectively. The bridging of the stationary contacts 88 by the movingcontact 8! completes a holding circuit for the energizing winding 81, ofelay 84, thereby maintaining relay 84 in cner. condition even if theparallel circuit, comple.cd by the stationary contact I2 and movingcontact H of the highfrequency relay 2-3 is opened. The bridgeing of thestationary contacts by the moving contact 92 completes an energizingcircuit for the closing coil I83 of the network circuit breaker Z-N.This energizing circuit may be traced from phase A of the networktransformer 2-T, stationary contacts 88 and moving contact IOI, of therelay 86, stationary contacts 188 and pallet switch IU'I of the networkcircuit (iii breaker Z-N, stationary contacts 89 and moving contact 92,of relay 84, energizing winding I93 of the network circuit breaker Z-N,stationary contacts 96 and moving contact 99, of relay 86, and thence tophase C of the network transformer 2-T.

The closing coil I63 is thereby effectively energized to close thenetwork circuit breaker 2-N and open the energizing circuit for theclosing coil H33 by moving the pallet switch I01 out of engagement withthe stationary contacts I06 and into engagement with the stationarycontacts I94. The opening of the circuit across the stationary contacts1'96 of the network circuit breaker Z-N also effects the deenergizationof the winding 81 of relay $6, and, assuming the other-than-normalfrequency control currents to be removed from the feeder circuitconnected to the network transformer Z-T, the high-frequency relay 2-Ris also deenergized and the contacts TI, 18, I9 and 8| are moved out ofengagement with the stationary contacts '12, 73, M and 16, respectively.Inasmuch as the other-than-ncrrnal frequency control currents areapplied to the feeder circuit only for the purpose of effecting theclosure of the network circuit breaker E-N and such control currents areremoved from the circuit upon the closing of the feeder circuit breaker,associated with the feeder circuit supplying power to the networktransformer fZ-T, the high-frequency relay 2-R will be deenergized andthe closing of the network circuit breaker 2-N effects thedeenergization of the relay 84 and the closing winding ")3 of thenetwork circuit breaker Z-N.

Next assume the network circuit breaker 9-N to be in its closedposition, the network transformer 6-T to be supplying power to thenetwork load circuit i, the network circuit breaker 2-N to be in itsopen position and the feeder circuit adapted to supply power to thenetwork transformer 2-T to disconnected from its associated bus or powersource. The sequence of control for effecting the closing or" thenetwork circuit breaker Z-N will now be considered.

As explained hereinbefore, the central station operator connects thehigh-frequency generator to the feeder circuit associated with thenetwork transformer Z-T, thereby effectively energizing the winding 'Hof the high-frequency relay Z-R. The energization of this relay resultsin the bridging of the stationary contacts 12 by the moving contact'i'i, thereby completing an energizing circuit for the winding 82' ofrelay 84. This energizing circuit is somewhat altered from the circuitdescribed hereinbefore when the network load circuit l was deenergized.

When the network load circuit I is energized from other networktransformers, the winding 93, of relay is energized to effect thebridging of stationary contacts 94- and 9! by the moving contacts 96 andml, respectively. The energizing winding 93 is permanently connectedacross phases A and C of the network transformer Z-T on the network loadside of the network circuit breaker 2-l l. The resulting energizingcircuit for the winding 9?, of relay 84, is therefore, traced from phaseA on the network load side of the network circuit breaker 2-N,stationary contacts 91, and moving contact IBI of relay 86, stationarycontacts 666 and pallet switch ID! of the open network circuit breakerZ-N, energizing winding 8'5 of relay 64, stationary contacts 12 andmoving contact If of the relay 2-R, stationary contacts 99 and movingcontact 99 of relay 86, and thence to phase C on the network load sideof the network circuit breaker Z-N.

The relay 86 is arranged to provide a proper potential for closing thenetwork circuit breaker Z-N. Under conditions when the network loadcircuit l is deenergized and it is desired to connect the transformer2-T thereto, the relay 86 remains deenergized and the contacts 96, 99and 98, llll thereof serve to partially complete the closing circuit ofthe network circuit breaker 1O 2-N. However, the circuit breaker 24*? isnot actuated to its closed position, under such conditions, until thecentral station operator closes the feeder circuit breaker and energizesthe network transformer 2-T. 15

When the network load circuit 1 is energized and it is desired toconnect the network transformer 2-T and associated feeder circuit tosupply power thereto, it may be necessary for the central stationoperator to effect a synchronizing of the 20 bus or source voltage withthe network load circuit voltage across the open feeder circuit breaker.This requirement necessitates the closing of the network circuit breaker2-N when the network load circuit I is energized and the feeder circuit5 breaker remains open. Under such system conditions the relay 66 isenergized to provide network potential for closing the network circuitbreaker Z-N.

The energizing of the winding 67, of the relay 3O 84, effects thebridging of stationary contacts 98 and 99 by means of the movingcontacts 9i and 92, respectively, and the bridging of stationarycontacts 89 by the moving contact 6| completes a holding circuit for thewinding 61. This hold- 35 ing circuit merely shunts theparallel-connected stationary contacts 12 of the high-frequency relayZ-R.

The bridging of the stationary contacts 89 by the moving contact 92, ofrelay 84, completes an 0 energizing circuit for the closing coil 4G3associated with the closing mechanism of the network circuit breakerZ-N. This energizing circuit may be traced from phase A on the networkload side of the open network circuit breaker Z-N, station- 45 arycontacts 91 and moving contact 59! of relay 86, stationary contacts I96and pallet switch i9! of the network circuit breaker Z-N, stationarycontacts 99 and moving contact 92 of relay 94, closing coil I93 ofcircuit breaker 2-N, stationary 50 contacts 94 and moving contact 99 ofrelay 86, and thence to phase C on the network load side of the networkcircuit breaker Z-N. As a result of the energization of closing coilI93, the network circuit breaker 2-N is actuated to its closed positionand the pallet switch I9! is moved out of engagement with the stationarycontacts I96, thereby deenergizing the winding 8'? of the relay 94.

The closing of the network switch 2-N results 60 in a voltage appearingon the primary side of the network transformer 2-T which is proportionalto the voltage on the network load circuit I. In accordance withtheexplanation detailed hereinbefore, the central station operator is re-65 quired to synchronize the two voltages appearing on the oppositesides of the open feeder circuit breaker at the source or bus end of thefeeder circuit adapted to supply power to the network transformer Z-T.

The high-frequency relay Z-R has the stationary contacts 13, 14 and 16and the moving contacts i8, i9 and 8!, thereof, so connected andarranged that the respective current transformer secondary windings I I9are adapted to be normally short circuitecl when the high-frequencycontrol currents are applied to the feeder circuit associated with thenetwork transformer il-T. It may be noticed that long as the relay Z-Rremains energized the current transformer secondary windings II 9 areshort circuited by means of r. v contacts 13-18, "-19 and 'I68I.

This arrangement prevents any effective energization of the currentwindings I I I of the sensi tive directional relays I38 until the feedercircuit, associated with the network transformer Z-T, is energized bythe closing of the feeder circuit breaker by the central stationoperator. As stated hercinbefore, the closing of the feeder cirbreakerautomatically results in the discon nection of the high-frequencycontrol source .rom the feeder circuit with the resultant deenergizationof ti. .2 higlr-frequency relay 2-R and the removal of the short circuitconnections for the current transformer secondary windings H9.

This short eircuiting connection is provided in order to prevent pumpingof the network circuit breaker Z-N when the sensitive directional relaysI08 are employer, and the circuit breaker 2-N is to be closed when thenet-work load circuit I is energized '3. other feeders or sources.

The necess by of employing such short circuiting means or some forrendering the sensitive directional iilB inoperative when the networkcircuit breaker E-N is closed. the network load circiut i is energizedand the feeder circuit breaker is open, is clearly apparent because thenetwork load circuit I is supplying magnetizing current for the networktransformer 72-1. The sensitive directional relays I89 are adjusted tobe effectively energized for such system energization conditions, and inview of such adjustment, the relays e made inoperative when the feedercircuit rer n unconnected to its bus or source and/or w n the other thannormal frequency control currents applied to the feeder circuit.

Inasmuch. as the l h frequency control currents are applied o for thepurpose of effecting the closure of the network circuit breaker Z-N, andare not utilized for effecting any control in the event of fault orother abnormal system conitions, the sensitive directional relays I98are provided and are operative to effect the opening of the networkcircuit breaker Z-N when both the circuit breaker and the networkcircuit eaker their closed positions and a predetermined power flowexists from the network load circuit 1 to the feeder circuit 2.

Sin the directional relays I08 are provided with a sensi'wc responsesetting, such that the .fiectivcly energized in accordance it flowing tothe network transformer 2-T from the network load circuit I,commensuwith the magnetizing current for such transformer, the networkcircuit breaker 2-N will be actuated to open position in response to theopening of the feeder circuit breaker by the central station operator.

Assuming a fault condition to occur on the feeder circuit associatedwith the network transformer I I-T or the opening of the feeder circuitbreaker in such. feeder circuit by the central station operator, thenetwork load circuit I supplies power to te fault through the networktransformer E-T or supplies the magnetizing current for suchtransformer. In accordance with this abnormal direction of power flow,the resulting torque of the relays ms is in the direction to effect thebridging of the stationary contacts I I! by the moving contacts I la.The bridging of the stationary contacts II I by the moving contacts H8completes a circuit for the tripping coil I02 of the network circuitbreaker Z-N.

This energizing circuit may be traced from phase C on the networktransformer side of the network circuit breaker Z-N, stationary contactsI I! and moving contacts I 58 of one or more of the directional relaysIilS, tripping coil H12 of the network circuit breaker Z-N, stationarycontacts IM and pallet switch Iii! of the circuit breaker 2-N, andthence to phase A on the network transformer side of the network circuitbreaker 2-N. The network circuit breaker 2-N is then actuated to itsopen position, and the pallet switch I01 is moved out of engagement withthe stationary contacts I04, thereby interrupting the energizing circuitfor the tripping coil 32 and bridging stationary contacts I06, in orderto partially complete the circuit for the closing coil I63 in the eventthat it is desired to reclose the network circuit breaker 2-N.

The directional relays I08, as indicated, are in- :d ho character, is tobe understood that any known type of sensitive relay means may beprovided in order to effect the opening of the network circuit breakersin an alternating current system of distribution.

In an alternating-current system of distribution employing insensitivedirectional relaying m ans, the control scheme shown in Fig. i of thedrawings provides a complete and satisfactory control and protectivemeans. The sequence of control, when insensitive directional relayingmeans are employed, will be detailed with reference to Fig. i of thedrawings.

The control and protective scheme, shown in Fig. is substantiallysimilar to the control and protective scheme shown in Fig. 3 with theexception of the directional relaying means employed and the esuitantsimplification of the highfrequency responsive relay Z-R. Thehigh-frequency relay t-R is provided with stationary contacts "I2 andmoving contacts TI, and such contacting means are arranged and connectedin a manner similar to the connection and arrangement of the contactingmeans I2 and H in the control scheme shown in Fig. 3.

Inasmuch as the directional relaying means shown in Fig. 4 of theinsensitive type, there is no possibility of the pumping of the networkswitch Z-N, when the network load circuit I is energized, the networkswitch Z-N is actuated to its closed position and the feeder circuitbreaker associated with the feeder circuit connected to the networktransformer 2-T remains in its open position. Since there is nopossibility of pun1ping of the network switch 2-N under such systemconditions, the short circuiting means for the current transformersecondary windings H9 is unnecessary, and the directional relays H18 maybe energized directly at all times from the current transformersecondary windings H9.

The insensitive directional relaying means shown in Fig. 4 arerepresented schematically as including the usual sensitive typedirectional relays Illll, similar to the directional relays I08 of Fig.3, and additional overcurrent relays I2| which are provided in order tosecure a high reverse current or insensitive setting of the directionalrelaying means.

The energizing means for the current and voltage windings III and H2,respectively, of the directional relays I08, are substantially the sameas the energizing connections shown in Fig. 3,

and the stationary contacts I I I are adapted to be bridged by themoving contacts I I8 when the directional relays IE8 are deenergized orpower is flowing from the network transformer 2-T to the network loadcircuit I.

-5 The overcurrent relays I2I are illustrated as including C-magnetstructures I22, current windings I23, disc members I24, spindles orshafts I26, spring-biasing means I27, magnetic damping means I28,stationary contacts I29 and moving 19 contacts I39. The current windingsI23 of the overcurrent relays I2i are connected in series with thecurrent windings III of corresponding directional relays I68, and thecurrent windings I23 are normally adapted to be short circuited by 1p;means of the bridging of the stationary contacts I II by the movingcontacts I I8 of the directional relays I08.

' Since the stationary contacts III are adapted to be bridged by themoving contacts H8 when 2,0 the network transformer 2-T is deliveringpower to the network load circuit I, and/or when the current transformersecondary windings II9 are deenerglzed, the overcurrent relays I2I areeffectively deenergized and the stationary contacts I29 thereof are notadapted to be bridged by the moving contacts I39 due to the biasingaction of the springs I21.

However, assuming a fault condition to occur on the feeder circuitassociated with the network 311;. transformer 2-T, the network loadcircuit I will deliver power to such fault through the networktransformer Z-T. The direction of current flow in the currenttransformer secondary windings II9 will be reversed and the movingcontacts H8 .3.. of the directional relays I98 will be moved out ofengagement with the stationary contacts II 1, thereby permitting theenergization of the current windings I23, of the overcurrent relays I2I,in accordance with the current flowing in the 40 current transformersecondary windings H9. The

overcurrent relays I2I are provided with suitable response settings,such that for fault conditions occurring on the feeder circuitassociated with the network transformer 2-T, or in the networktransformer 2-T itself, the moving contacts I30 of one or more of theovercurrent relays I2I will be actuated to bridge their respectivestationary contacts I29 to thereby result in the actuation of thenetwork circuit breaker 2-N to its 50, open position. i

The stationary contacts I29 of the overcurrent relays I2I are connectedin parallel, and the energizing circuit for the tripping coil I02 of thenetwork circuit breaker 2-N may be traced from 55;. phase C on thenetwork transformer side of the network circuit breaker 2-N through oneor more of the stationary contacts I29 and moving contactsI39, of theovercurrent relays I2I, energizing winding I92, of the network circuitbreaker 2-N, stationary contacts I94 and pallet switch I01 of thecircuit breaker 2-N, and thence to phase A on the network transformerside of the network circuit breaker 2-N.

It is to be understood that the combination of the directional relaysI08 and the overcurrent relays I2I are utilized only for the purpose ofproviding an insensitive directional relaying means, and any suitableinsensitive directional relaying means is understood as being contem-71); plated in the scope of the present invention.

In the various figures of the drawings and in the foregoing description,reference has been made to the use of a single-phase high-frequencygenerator for applying other than normal fre- 75'; quency controlcurrents to the respective feeder circuits. Obviously, a polyphasehigh-frequency generator, or any type of tube oscillator, or other thannormal frequency means, may be employed for the control and protectivemeans disclosed in the present invention, and provides substantially 5the same operating results.

Assuming a polyphase high-frequency generator to be utilized, it wouldbe necessary to provide a plurality of high-frequency responsive relaysZ-R in the Fig. 3 and Fig. i arrangements, 10 and to connect therespective contacts thereof in parallel. Inasmuch as the provision of aplurality of relays 2-R. in the Fig. 3 arrangement would result in anexcessive number of relay contacts, an auxiliary relay could easily beprovided for normally short circuiting the current transformer secondarywindings H9, and the energization of such relay could be controlled inaccordance with the energization of the high-frequency relays 2-R.

In the foregoing description of the'control sequence included in thepresent invention, it will be noted that a complete control andprotective system has been provided for an alternating-current system ofdistribution, wherein other than normal frequency control currents areutilized for effecting the closure of the network circuit breakers,while usual network or directional relays may be utilized in conjunctionwith such other than normal frequency control for effecting the openingof the network circuit breakers under predetermined system conditions,depending upon the characteristics of the particular network system towhich the present invention is applied.

It may readily be seen, therefore, that the present invention may beutilized in existing alternating-current network systems and in anyfuture network systems, wherein the control schemes of the prior art areobjectionable from 49 either an operating or an economical standpoint.

It is proposed, therefore, that the present invention shall not belimited to the specific embodiments disclosed in the presentapplication, in view of the basic nature of such invention, and nolimitations should be imposed thereon other than as indicated in theappended claims.

I claim as my invention:

1. In an alternating-current system of distribution, a supply circuit, anetwork load circuit, 5 a network switch connecting said circuits, meansfor supplying other-than-normal frequency control currents to one ofsaid circuits, and control means for said network switch, said controlmeans including means directly responsive to a fault on said supplycircuit for causing said switch to, open, and closing means for saidswitch, said closing means including means responsive to saidother-than-normal frequency currents.

2. In an alternating-current system of dis- 50 tribution, a supplycircuit, a network load circuit,

a network switch connecting said circuits, means for supplyingother-than-normal frequency control currents to one of said circuits,and control means for said network switch, said control 5 meansincluding directionally responsive means for effecting the opening ofsaid switch in response to a fault on said supply circuit, and closingmeans for said switch, said closing means including means responsive tosaid other-than-normal frequency currents.

3. In an alternating-current system of distribution including a supplycircuit, a circuit breaker in said supply circuit, a network loadcircuit and a network switch connecting said cir- 76 cults, thecombination including a source of other-than-normal frequency currents,a circuit interrupter connecting said source with said supply circuit,control means for automatically controlling the actuation of saidnetwork switch including means responsive to the source currents forclosing said network switch and power directional relay means foropening said network switch and means for closing said circuitinterrupter.

4. In an alternating-current system of distrlbution including a supplycircuit, a circuit brcaker in said supply circuit, a network loadcircuit and a network switch connecting said circuits, the combinationding a source of otherthan-normal frequency currents, a circuitinterrupter connecting said source with said supply circuit, controlmeans for automatically controlling the actuation of said network switchincluding power directional relay means for opening said network switch.means for closing said circuit interrupter and means controlled by saidcircuit breaker for opening said circuit intercircuit breaker is closed.

"natingwurrent system of dison including a supply circuit, a circuit insaid supply circuit, a network load lid network switch connecting saidiits, the combination including a source or ran-normal frequencycurrents, a cirt interrupter connecting said source with said ly controlmeans for said network switch including means responsive to said sourcecurrents for closing said network switch and power directional relaymeans for opening said network switch, means for closing said circuitrelay means for opening said cir- 1' i 1 errupt t interrupter after apredetermined time delay controlled by the closing of said circuitbreaker for opening said circuit interrupter.

6. In an alternating-current system of distribution including a supplycircuit, a circuit breakin supply circuit, a network circuit and anetwcr: switch connecting said circuits, the combination including asource of other-thanncrmal frequency currents, a circuit interruptercorrecting said source with said supply circuit, or rel means for saidnetwork switch including closing means responsive to the source currentsand opening means responsive to power flow -=e network load circuit tothe supply circuit, means for closing said circuit interrupter meanscontrolled by said circuit breaker for said circuit interrupter upon theclosing of said circuit breaker.

'7. In an alternating-current system of distrion including a supplycircuit, a circuit breake1. in said supply circuit, a network loadcircuit and a network switch connecting said circuits,

combination including source of other- --norinal freque cy currents, acircuit interrupter o cting said source with one of said circuits, relmeans for said network switch including a sensitive power directionalrelay for opening said network switch and closing means for said networkswitch including means responsive to said otlier-tlian-no11nal frequencycurrents.

8. In an alternating-current system of distribution including upplycircuit, a circuit breaker in said supply circuit, a network loadcircuit and a network switch connecting said circuits, the combinationincluding a source of otherthan-normal frequency currents, a circuitinterrupter connecting said source with said supply clrcuit, controlmeans for said network switch including closing means responsive to thesource currents and sensitive power directional relay means for openingsaid network switch, means 5 for closing said circuit interrupter,time-delay means for opening said circuit interrupter, means for closingsaid circuit breaker, means controlled by the closing of said circuitbreaker for opening said circuit interrupter and relay means 10associated with said supply circuit and said circuit breaker for openingsaid circuit breaker under predetermined abnormal conditions 01 saidsupply circuit.

9. In an alternating-current system 0! dis- 15 tribution including asupply circuit, a circuit breaker in said supply circuit, a network loadcircuit and a network switch connecting said circuits, the combinationincluding a source 0! other-than-normal frequency currents, a cirm cuitinterrupter connecting said source with one or said circuits, controlmeans for said network switch including sensitive power directionalmeans for opening said network switch, means for closing said circuitinterrupter and means 35 responsive to the source currents for renderingsaid sensitive power directional means ineficctive when said circuitinterrupter is closed.

10. In an alternating-current system or distribution including a supplycircuit, a circuit breaker in go said supply circuit, a network loadcircuit and a network switch connecting said circuits, the combinationwith a source of other-than-normal Ire quency currents, a circuitinterrupter connecting said source with said supply circuit, control umeans for said network switch including closing means responsive to thesource currents and sensitive power directional means for opening saidnetwork switch, said closing means being eflective to render saidopening means lnefiectively u energized when said circuit interrupter isclosed. means for closing said circuit interrupter and means controlledby the closing of said circuit breaker for opening said circuitinterrupter.

11. In an alternating-current system or distribution including a supplycircuit, a circuit breaker in said supply circuit, a network loadcircuit and a network switch connecting said circuits, the combinationincluding a source of other-than-normal frequency currents, a circuit ninterrupter connecting said source with one or said circuits, controlmeans for said network switch including insensitive power directionalmeans for opening said network switch and closing means for said networkswitch including ll means responsive to said other-than-normal frequencycurrents, means for closing said circuit interrupter and meanscontrolled by said circuit breaker for opening said circuit interrupterwhen said circuit breaker is closed.

12. In an alternating-current system of distribution including a supplycircuit, a load circuit and a circuit breaker connecting said circuits,the combination including a source of otherthan-normal frequencycurrents, a circuit interrupter connecting said source with one of saidcircuits, control means for automatically controlling the actuation ofsaid circuit breaker including closing means initiated by the sourcecurrents and insensitive power directional means for I. opening saidcircuit breaker and means for closing said circuit interrupter.

13. In an alternating-current system of distribution including a supplycircuit, a circuit breaker in said supply circuit, a network load clr-II cuit and a network switch connecting said circuit, the combinationincluding a source of otherthan-normal frequency currents, a circuitinterrupter connecting said source with said supply circuit, controlmeans for said network switch including closing means initiated by saidsource currents and insensitive power directional means for opening saidnetwork switch, means for closing said circuit interrupter, time delaymeans for opening said circuit interrupter, means controlled by theclosing of said circuit breaker for opening said circuit interrupter andrelay means associated with said supply circuit and said circuit breakerfor opening said circuit breaker under predetermined system conditions.

JOHN S. PARSONS.

